Solar Roof
 

My coolest mod yet!
http://4.bp.blogspot.com/_2A3Fl4I3bz...arRoof+017.jpg
More photos and details than you'd ever want on my blog:
Scientific Method meets Fuel Economy: SolarArray

That's nifty...like it! Forgive my ignorance but what are you powering in the car with the energy it generates and will it (or how will it) help FE?

Matt,
It's going to augment my alternatorless-ness. Nothing now - but I have plans for it. Daox, Orange4boy, and I have been working on a solution for low voltage issues.
I have a trickle charger already, but this is fun, cool, and a step toward learning about solar. I don't want to spend $500 on an inverter system until I can get a simple battery system working well.

Thanks for the info. and was interesting reading your build blog too! Great pics and good to hear the wife is on board as well...never hurts to have a little support. Best of luck and will be following your progress!

How much does the setup add in weight?

Have you considered also using the hood?

How much do you think the panels you used cost?

Have you considered getting packs of "Damaged" panels from eBay?

I wonder if the hood is a good idea. First, at certain angles it could cause more glare than the normal hood paint job, blinding the driver. Second, the hood gets warm when after the engine has been operating, and solar cells' efficiency decreases with temperature.

I'm also interested in weight.

gascort -

:thumbup:

100 Watts in 4-5 hours of sun. How many daytime alternator-less miles does this translate to?

CarloSW2

Nice roof panel! I like the tree /power lines reflection. Looks like power palm trees. Very post modern metaphor.

For 5 hours charging at 100 watts that's 40 AH theoretical before losses. Not too shabby.

I need one for my Kammback...

Keep on amping!

That is really sweet! I love how you have so much area you can use. I'm a bit jealous of that, haha.

Just the other day I was talking to SVOboy about doing something similar. My idea was to use my sunroof and paste the cells to the bottom side of it. This wouldn't nearly the area yours does though.

With you pumping out that many amps, you're probably gonna wanna pick yourself up a charge controller too I'd imagine.

Basically nothing. Each "string" of 14 cells in series weighs less than one pound. I had to keep them from blowing in the wind as I lifted them up and set them in place. The plexiglass is 95+% of the added weight, and it's probably about 20 pounds. It would be about 10 pounds if I wasn't stupid and got the right thickness (the thinnest Lowes sells is much more flexible than what I got)
Yes! I have one string producing 7.25V up there that I can't come up with a use for unless I add more somewhere else later. I was thinking probably the hood, or also a neat idea would be the top 6" of the windshield, where it's tinted dark blue or black anyway. Hood is the flattest, and most ideal, though.
They were $2.50 each. Each was rated at 1.8W
These are those ones from Ebay, and most looked like new. Some had chipped edges, and a couple had cracks. Even the cracked ones work fine.
I got them from ebay seller fred480V, it looks like he sells lots of solar cells from his feedback, and he's got some new ones for sale now that are way more powerful than these. His auctions state something like, "best in the world right now" or "best available on Ebay at this time"

Good points - I'm a bit worried about glare too - will have to test with my spare plexi.

The car probably uses about 300W to drive, plus more for the starter, but that's hard to quantify - I could probably look it up. Assuming 100% efficiency (which my battery and is not) it would be 1/3 of my good sun time. So probably 1.5 hours after efficiency losses and starter use. My commute is only 20 minutes each way, so I should be good without even needing my trickle charger for an average week.

Dude, your roof would be great! Probably 2X the area of mine unless it has a sunroof and weird bump in the middle like mine does.

lol, I wasn't even looking for a wagon originally. Everything about it has worked out nicely though; extra space for hauling since I got rid of my truck to buy it, extra room for baby stuff since we had a little one, easier to attach Kammback, and more room for solar array. :)
I want to build a charge controller. We'll see if I get it built or if I go to Ebay first. :)

This is exactly what I was trying to tell you to do! Exit roof, enter solar!

That's cool. Doesn't look like it would cut into your aero either. Looks great!

I could put a lot of those on the roof of the wagon. Don't think I could go alternatorless though, besides long trips, my engine is a beast compared to the Escort engine (used to have a 92 Escort wagon).

I did some digging for you (and me). I ended up finding this. Doesn't get much cheaper than this. ~$15 for the kit shipped. It also is a dump load charge controller, so you could say... power your fan if your battery gets fully charged ah-la Prius III. That would be pretty sweet. :)

ghurd - Hurd Solar Renewable Energy | Dump Controllers

Thanks, Daox - the kit is probably the way to go - I want to get my hands dirty, so to speak, but learn how it works at the same time.
Powering the fan like the prius is a good idea, or if I eventually have an array (planned) atop my garage, I could plug the car's dump load into the inverter! Vehicle -to- Grid!
My car doesn't move much in the summer unless we go out of town; I live in the city, don't work all summer, and ride my bike or walk everywhere I can.

Update - after 2 days of sitting/driving in the sun, no cracks - well, no spreading of the cracks I created. I will take it on the highway tomorrow up to 70 mph so hope everything goes well. I also noticed that since this raised the back end of my roof by about 8mm(the roof curves steeply there so I put washers beneath the plexi and didn't make it conform to the roof's curve), I need to put a couple of washers under the leading edge of my Kammback - it was very perfect and smooth, but now there's a drop-off.
I got the wires ready to install a charge controller, just have to wait for a paycheck to purchase the kit that Daox pointed out.
I also decided on a use for the spare 7.5V string I have up there until I install more on the hood or Kammback - charging my daughter's EV (power wheels ATV) - it's a 6V battery. ;)

Gascort,

If you have cracks in the plexi, drill a hole (with a dullish drill*) just at the end of the crack then fill the hole with silicone. This is a stress relief technique, that spreads the forces around the circumference of the hole. Stops cracks in their tracks...:thumbup:

*plastic drills should be ground so the cutting edge has a 90 degree rake. You want to scrape the plastic. A normal twist drill will dig in and force the drill through too fast, causing fractures. Barring a way to regrind, use a dullish one, go slow and watch out for overheating. A glass of water can be helpful to cool off the drill if you are doing a lot.

Ahh... I noticed my cracks were when I pressed too hard/too fast or when the plexi was unsupported from the bottom. When I fed the bit in more slowly, it didn't cause a problem. I may try the stress relief tactic on one of those cracks that's in a bad location... thanks!

Wow, gascort! Awesome!!! :cool:

I also went through your blog. Great things you are learning, there! :thumbup:

I'll have to think about scheduling another Kansas/Missouri meet just so I can get to see all of that in the flesh!!!

(Only this time no "Meet in the heat"...) :o

If your battery gets fully charged when sitting for a long time, is there a way to run an isolated block heater with the extra energy? Since your commute is fairly short this may reduce open loop time.

Don

There is; the dump controller can put extra charge into anything; a plain old resistive block heater would work as a dump load, even if it's set up for 120V.
Will it warm up the motor? Not even close to significantly, but every bit helps I guess.
I'm going to try to dump the extra juice in the summer to the car's fan; it will be interesting to see if it can start the fan without a capacitor and some extra circuitry.

lol, I just realized I can connect the extra power coming from the panels to a simple car relay to turn the fan on/off - no capacitor needed.

This is so fantastic :thumbup: and I'm so jealous...

A few days ago while I was EOC behind a Prius I was thinking : "my PZEV is solar". Now I'm so ashamed with my small 1.5W amorphous panel...
Spent a couple hours to search the French web to find some solar cells, but these are 5 times more expensive than buying a solar panel... I found a couple solar cells kits on US ebay, some delivers to Europe and one is for newbies :) Now I know my next project ;)

Denis.

Literally. With the extra layer on top of the roof, the inside of the car should that much cooler:)

Gascort, did you see any difference in MPG before and after solar roof?

My result:
5WT Solar trickle charger on my 09 Hyundai Sonata(25-32MPG by fueleconomy.gov).
On my trip to Florida I've got 37MPG. Drove about 75MPH, AC mostly on.
From Florida i drove at night and MPG was 33MPG(75-80MPH, NO AC).
*Regular driving(30%city-70%highway) results: 534 miles on 15.6 gallons = 34.2MPG.

idiom,
If you have a scanguage, an ABA test would be much more informative.

I don't have scanguage. All my calculations based on mileage divided to gas fill up amount. I think it should be more accurate than any tool?:D
Just bought 36 6x6 new solar cells for 115.

Well, yes and no. To really gain a good understanding of your improvement, you need to test it under as near identical conditions as possible. With solar cells connected, make a short back-and-forth run on a road with no stop lights and little other traffic. Make the same run with the cells disconnected. Run the route yet again with the cells reconnected. Check results after each run.
It's difficult to compare results on runs such as yours. Is there an elevation difference? Difference in traffic loads? The idea is too eliminate as many variables as possible, otherwise your results are, statistically speaking, contaminated.

You could do a set up like this and put in a second battery.

How long do you think it would take to completely charge your one battery sitting in the sun without using the car?

Not on my new car. I'm planning a total conversion for my 98 Altima or some other "candidate".
But it's just a plan, have not much time to spend and need some space, tools and help with project.

I don't know how long it'll take to charge. But i know it's not much you can get from Solar. Maybe about 5-10 miles per day?...

I know where my next paycheck is going! However, I'm still debating on whether or not to custom build the panel like Gascort, or buy a premade panel all assembled nice and neat. I know if i build it, it will cost half as much, however, I don't to ruin my paint on my car.

However, if i buy a premade panel, i can just place it right on top of my flat trunk.

Hm, decisions....

I was imagining building my own with coroplast as support, so the panel will be light and may be foldable. I could use it as a windshield sun reflector when I park :cool: but may not be for this year.

Denis.

How flexible are the solar cells? Will they easily bend into non-complex shapes, or will I need to hammer out my roof?

I don't care, I'll do what I gotta do if I decide to do this, but if the cells will flex and fill in the areas between the rises in the roof line, I'd rather do that.

I believe the ones he purchased (and are only on sale) on ebay are the mono/poly-crystaline type that come in small plates (generally 2"x3" or 2"x2", but they come in all sorts of sizes). They are not flexible at all, in fact, the Mono are the most delicate (yet most efficient) and crack easily. Polycrystaline are more durable (not as efficient) and Amorphous are the most durable (but least efficient).

If you want a flexible cell, you need to look into the Amorphous types. However, these are the lease efficient type of solar cell available.

Mono = Best
Poly = Better
Amorphous = Good

Well, I guess I'll have to look into flattening the roof somehow, then.

or you could build a custom tray to place on top of your roof, then put the solar cells in the tray.

or you could put the smaller cells in between the ridges

I was thinking more like cutting out the upper panel of the roof, and putting a flat sheet in about 3/8" deeper, so that the cells and the plexi would match up to the original roof line, nix the ridges altogether.

I also have about 3-4 sqft of black dash panel that does nothing except collect sunlight all day... I think I could use that also, if I ended up with extra cells.

Better to tab the cells together for 14V?